organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
from butadiene and substituted N-arylmaleimides have been
reported, in contrast to almost 40 unsubstituted adducts
(Cambridge Structural Database; Version of May 2005; Allen,
2002). Previously, the molecular and supramolecular struc-
tures of two Diels±Alder adducts between ortho- and para-N-
acetoxyphenylmaleimides and -furan were reported (Trujillo-
Ferrara et al., 2004). The molecular and supramolecular
structures of the Diels±Alder adducts 2-(1,3-dioxo-
2,3,3a,4,7,7a-hexahydro-1H-isoindol-2-yl)phenyl acetate, (I),
and its para isomer (II), are analyzed here.
ISSN 0108-2701
Two isomeric butadiene±N-(acetoxy-
phenyl)maleimide Diels±Alder
adducts: supramolecular structure
directed by CÐHÁ Á ÁX (X = O and p)
hydrogen bonds and perpendicular
dipole carbonyl±carbonyl interactions
a
b
Â
Jose G. Trujillo-Ferrara, Rosa Luisa Santillan-Baca,
b
c
Â
Â
c
Â
Norberto Farfan-Garcõa, Itzia I. Padilla-Martõnez and
Â
Â
Â
Efren V. Garcõa-Baez *
Compounds (I) and (II) crystallize in the monoclinic space
groups P21/n and P21/c, respectively. Their molecular struc-
tures are shown in Figs. 1 and 2, and selected bond lengths and
angles are listed in Tables 1 and 3, respectively. In both
compounds, the succinimide group (C1/O1/N2/C3/O3/C3A/
a
Â
Â
Seccion de Graduados y Departamento de Bioquõmica, Escuela Superior de
Medicina, Instituto Politecnico Nacional, Mexico DF 11340, Mexico, bCentro de
Â
Â
Â
Investigacion y Estudios Avanzados del Instituto Politecnico Nacional, Avenida IPN
2508, Mexico DF 07330, Mexico, and cUnidad Profesional Interdisciplinaria de
Â
Â
Â
Biotecnologõa, Instituto Politecnico Nacional, Avenida Acueducto s/n, Barrio La
Â
Â
Laguna Ticoman, Mexico DF 07340, Mexico
Ê
C7A) has an r.m.s. deviation from the mean plane of 0.002 A,
Correspondence e-mail: vgarcia@acei.upibi.ipn.mx
and the cyclohexene ring exhibits a boat-like conformation.
The benzene ring is twisted relative to the succinimide ring by
89.7 (1)ꢀ in (I), the ortho isomer, and by 61.9 (1)ꢀ in (II), the
para isomer. These results are in agreement with the expected
values for the twist necessary to relieve unfavorable steric
interactions between the o-acetoxy group, on the benzene
ring, and the succinimide carbonyl groups. The twist exhibited
by (I) is equivalent to the value found in other ortho-tert-butyl
(Curran et al., 1994) or F-substituted Diels±Alder adducts (Li
et al., 2005), but in this last compound and in (I), the ortho
substituent points to the folded face of the cyclohexene ring.
The acetoxy group is twisted by 66.0 (1) and 70.0 (1)ꢀ from the
mean plane of the benzene ring in (I) and (II), respectively.
These values contrast with the broad range found for Diels±
Received 1 September 2005
Accepted 18 January 2006
Online 11 February 2006
The molecular and supramolecular structures of 2-(1,3-dioxo-
2,3,3a,4,7,7a-hexahydro-1H-isoindol-2-yl)phenyl acetate, C16-
H15NO4, (I), and its para isomer, 4-(1,3-dioxo-2,3,3a,4,7,7a-
hexahydro-1H-isoindol-2-yl)phenyl acetate, (II), are reported.
The torsion angle between the succinimide and benzene rings
depends on the position of the acetoxy substitution [89.7 (1)
and 61.9 (1)ꢀ for (I) and (II), respectively]. The twist of the
acetoxy group relative to the mean plane of the benzene ring
is almost independent of the acetoxy position [66.0 (1) and
70.0 (1)ꢀ]. Packing interactions for both compounds include
soft CÐHÁ Á ÁX (X = O and Ph) interactions, forming chains of
centrosymmetric dimers and interlinked chains for (I) and
(II), respectively. In addition, three perpendicular dipole
C OÁ Á ÁC O interactions contribute to the supramolecular
structure of (II).
Comment
Substituted N-arylmaleimides have been used to control the
stereochemistry of Diels±Alder cycloadditions (Kitagawa et
al., 1998). Depending on the appropriate selection of the
ortho substituent, the NÐAr torsion angle and the barrier to
rotation are increased in comparison to those in the unsub-
stituted N-arylmaleimides (Curran et al., 1994). More recently,
molecular induced recognition between the diene and the
maleimide have been used to control the stereochemistry of
cycloaddition reactions (Bennes et al., 2001). However, the
X-ray structures of only ®ve Diels±Alder adducts derived
Figure 1
The molecular structure of the title ortho Diels±Alder adduct, (I), with
displacement ellipsoids at the 30% probability level.
Acta Cryst. (2006). C62, o125±o128
DOI: 10.1107/S0108270106002186
# 2006 International Union of Crystallography o125